Excellent sale price for the Cambridge Audio DACMagic XS:
http://www.musicdirect.com/p-232839-cambridge-audio-dacmagic-xs.aspx
(if it's on sale at Music Direct, it may be even cheaper elsewhere, so search around)

Plug this into a laptop's USB2 socket, install the Cambridge USB2 driver, and dig how much better 
everything sounds, especially using high-grade headphones. This thing has enough umph to drive 
Sennheiser HD650 headphones as loud as I'd ever want to listen, and comfortably drives 
Audio-Technical ATH-M50 headphones or any other low-impedence professional sealed-ear variety.

Note that with the USB2 driver installed, it works in true HD mode (up to 192/24). I figured just 
the extra power from a real-deal headphone amp would be an upgrade from the headphone jack on my 
Lenovo laptop, but everything immediately sounded much better. In fact I trust the output of the 
DACMagic enough to do for-hire editing and processing on the laptop while travelling, using a 
known/trusted pair of headphones. The 1/8" output also comfortably drives any line input, so it can 
be used as a regular DAC hooked up to an amp or amplified speakers. This is one of those devices 
that I'm amazed can be so good for so cheap, and I paid $150 for mine.

-- Tom Fine